1. Field of the Invention
The instant disclosure relates to a fingerprint reading system; in particular, to a non-contact fingerprint reading system.
2. Description of Related Art
Personal electronic devices such as laptops or mobile phones typically retain user's personal information. To prevent others from obtaining personal information, access password is usually pre-set by the user to gain access to the personal electronic devices. However, access password can still be bypassed easily by other manners, thus allowing others to obtain personal information.
Contact optical fingerprint readers are available that provide bright and dark fingerprint images because of full reflection of light onto the surface of a prism is intercepted by the ridge on a finger. However, the bulk volume and cost of the prism in the contact optical fingerprint reader are quite high, and the surface of the prism requires surface treatment to prevent scratches and corrosive damages while fingers can easily leave dirt on the surface of the prism that requires cleaning, all of which prevent the readers from accurate authentication. Moreover, the contact type readers cannot identify real fingerprints from synthetic fingerprint.
Although non-contact fingerprint readers typically are also available, conventional non-contact fingerprint readers typically include micro lenses to obtain high resolution fingerprint images and require close enough distance to the finger in order to provide sufficient magnification and clear fingerprint images. Not only is the depth of field shallow, but finger support mechanism is also required to fix the finger's position. Alternatively, an expensive and high-end macro lens is required to provide deep depth of field effects in close proximity.
To address the above issues, the inventor strives via associated experience and research to present the instant disclosure, which can effectively improve the limitation described above.